Fix p/kWh figures, fix Predheat cost calculation, new glitch filter

What's Changed

### Fixes

• Fixing p/kWh calculations by @springfall2008 in #1605

The p/kWh calculation didn't work very well as it was based on energy imported-exported which can be close zero creating spikes. Changed the calculation to use load energy and account for the change in current battery level in the estimated cost.

• Predheat cost calculation was broken by @springfall2008 in #1610

Preadheat cost calculation was totally wrong due to a typo, fix this.

• Glitch filter for incrementing data by @springfall2008 in #1606

Remove single datapoint glitches on incrementing data e.g. load_kwh, if a value goes up and then returns back down again the spike is removed.

• Fix Changed to Error: Exception raised local variable 'day_load_pkwh' referenced by @springfall2008 in #1608

YAML Template updates

• Change of Octopus Intelligent GO ready time sensor name to match latest integration by @springfall2008 in #1609
• Add template for LuxPower inverters by @raldred in #1594

New Contributors

• @raldred made their first contribution in #1594

Full Changelog: v8.5.9...v8.5.10